Java学习笔记——三层架构

Layer:

UI层:　　user interface 用户接口层

Biz层:　  service business login layer 业务逻辑层

DAO层:   Date Access Object 数据访问层

1.建立三层架构

UI层(对应包ui):这里就是一个简单的测试类

Biz层(对应包service):包括实体类的service层接口IGradeService和其实现类(impl包下)GradeServiceimpl

DAO层(对应包dao):BaseDAO工具类和实体类的dao层接口IGradeDAO和其实现类(impl包下)GradeDAOimpl

BaseDAO代码:

package cn.happy.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

/**
 * database Data Access Object
 * 数据库访问工具类
 * Created by yanshaochen on 17-7-25.
 */
public class BaseDAO {
    static final String URL="jdbc:mysql://127.0.0.1:3306/t14";
    static final String DRIVER="com.mysql.jdbc.Driver";
    static final String USR="root";
    static final String PASSWORD="root";
    private Connection con=null;
    private PreparedStatement ps=null;
    private ResultSet rs=null;
    //getConnection
    public Connection getConnection() throws Exception {
        Class.forName(DRIVER);
        if(con==null||con.isClosed()){
            con= DriverManager.getConnection(URL,USR,PASSWORD);
        }
        return con;
    }
    //close rs,ps,con
    public void closeResources() throws Exception {
        if(rs!=null)
            rs.close();
        if(ps!=null)
            ps.close();
        if(con!=null)
            con.close();
    }
    //executeUpdate
    public int executeUpdate(String sql,Object... objs) throws Exception {
        int count=0;
        getConnection();
        ps=con.prepareStatement(sql);
        if(objs!=null){
            for (int i=0;i<objs.length;i++){
                ps.setObject(i+1,objs[i]);
            }
        }48         count=ps.executeUpdate();
        return count;
    }
    //executeQuery
    public ResultSet executeQuery(String sql,Object... objs) throws Exception {
        getConnection();
        ps=con.prepareStatement(sql);
        if(objs!=null){
            for (int i=0;i<objs.length;i++){
                ps.setObject(i+1,objs[i]);
            }
        }60         rs = ps.executeQuery();
        return rs;
    }
}

实体类代码:

package cn.happy.entity;

/**
 * Created by yanshaochen on 17-7-25.
 */
public class Grade {
    private String gradeName;

    public String getGrade() {
        return gradeName;
    }

    public void setGrade(String gradeName) {
        this.gradeName = gradeName;
    }
}

Biz层接口代码:

package cn.happy.service;

import cn.happy.entity.Grade;

/**
 * Created by yanshaochen on 17-7-25.
 */
public interface IGradeService {
    boolean addGrade(Grade grade) throws Exception;
}

实现类代码(与dao层联系):

package cn.happy.service.impl;

import cn.happy.dao.IGradeDAO;
import cn.happy.dao.impl.GradeDAOImpl;
import cn.happy.entity.Grade;
import cn.happy.service.IGradeService;

/**
 * Created by yanshaochen on 17-7-25.
 */
public class GradeServiceImpl implements IGradeService {
    IGradeDAO dao=new GradeDAOImpl();
    @Override
    public boolean addGrade(Grade grade) throws Exception {
        return dao.addGrade(grade);
    }
}

DAO层接口代码:

package cn.happy.dao;

import cn.happy.entity.Grade;

/**
 * Created by yanshaochen on 17-7-25.
 */
public interface IGradeDAO {
    boolean addGrade(Grade grade) throws Exception;
}

实现类代码:

package cn.happy.dao.impl;

import cn.happy.dao.BaseDAO;
import cn.happy.dao.IGradeDAO;
import cn.happy.entity.Grade;

/**
 * Created by yanshaochen on 17-7-25.
 */
public class GradeDAOImpl extends BaseDAO implements IGradeDAO{
    @Override
    public boolean addGrade(Grade grade) throws Exception {
        boolean flag=false;
        String sql="insert into grade(gradeName)values(?);";
        int count = executeUpdate(sql,grade.getGrade());
        if(count>0){
            flag=true;
        }
        return flag;
    }
}

测试类代码:

package cn.happy.ui;

import cn.happy.entity.Grade;
import cn.happy.service.IGradeService;
import cn.happy.service.impl.GradeServiceImpl;

/**
 * Created by yanshaochen on 17-7-25.
 */
public class MyMain {
    public static void main(String[] args) throws Exception {
        Grade grade = new Grade();
        grade.setGrade("T21");
        IGradeService igs=new GradeServiceImpl();
        boolean isSuccess = igs.addGrade(grade);
        if(isSuccess){
            System.out.println("添加成功!");
        }else {
            System.out.println("添加失败!");
        }
    }
}